Growing on old leaves. The plasmodiocarp forms very much flattened irregular patches from a few to several millimeters in length or extent. I am indebted to Dr. Geo. A. Rex, of Philadelphia, for the identification of my specimens, with those in the herbarium of Schweinitz, under the name of Physarum effusum.
IV. LEPIDODERMA, DeB. Sporangium stipitate or sessile, sometimes plasmodiocarp; the wall a thin, firm, colorless membrane, with an outer layer of large scales consisting of bicarbonate of lime, the scales either lying upon the wall or inclosed in lenticular cavities of the membrane. Stipe present or absent; the columella usually conspicuous. Capillitium of very slender threads, simple or outwardly branching at a sharp angle, connected at the extremities. Spores globose, violaceous.
"In the present genus the carbonate of lime is present in the form of very minute amorphous lumps until near to maturity, when it is dissolved and reappears as bicarbonate of lime deposited in comparatively large flakes."—Massee.
1. Lepidoderma tigrinum, Schr. Sporangium large, much depressed, hemispheric or lenticular, the base umbilicate, stipitate; the wall a firm, dark colored membrane, variegated with large and small irregular shining scales, greenish-yellow or straw color, rupturing irregularly. Stipe stout, thick, erect, rugulose, ochraceous or ferruginous, variable in length, expanding at the base into a thin hypothallus; the columella brown, convex or hemispheric. Capillitium of slender, dark colored threads, simple or sparingly branched, radiating from the columella to the wall. Spores globose, minutely warted, dark violaceous, 10–13 mic. in diameter.
Growing on old wood, moss, etc. Sporangium 1–1.5 mm. in diameter, the stipe 1 mm. or less in length. This appears to be the only species of the genus thus far discovered in this country.
- Fig. 37.—Didymium proximum, B. & C. a. Sporangium and stipe × 33. b. Section through the columella.
- Fig. 38.—Didymium eximium, Peck. a. Showing the rough columella of one form. b. Section through the discoid columella of the very much depressed form. Magnified by 33.
- Fig. 39.—Didymium minus, Lister. a. Sporangium and stipe × 33. b. c. d. Sections through the columella showing different forms.
- Fig. 40.—Didymium farinaceum, Schr. Section through the columella. After Rostafinski.
- Fig. 41.—Didymium anellus, Morgan, a. Growing upon a leaf × 3. b. Plasmodiocarp × 17.
- Fig. 42.—Spumaria alba, Bull. Var. 1. didymium, sporangia × 3. Drawn from a foreign specimen.
- Fig. 43.—Spumaria alba, Bull. a. Æthalium natural size. b. Capillitium and spores as seen by a magnifying power of 500 diameters.
- Fig. 44.—Diderma floriforme, Bull. Stipe and columella × 20.
- Fig. 45.—Diderma crustaceum, Peck. a. Sporangia crowded on the thick hypothallus, natural size. b. Sporangia × 11. c. Section through outer coat, inner membrane, and columella.
- Fig. 46.—Diderma cinereum, Morgan, a. Sporangia growing on a leaf × 3. b. Sporangia × 23. c. Section through the wall and columella.
- Fig. 47.—Diderma reticulatum, Rost. Plasmodiocarp growing on leaf × 3.
- Fig. 48.—Diderma effusum, Schw. Plasmodiocarp effused on a leaf × 3.
The Journal of the Cin. Soc. Natural History
Vol. XVI. Plate XII.